298 Profs. Percy Frankland aud Marshall Ward. 



Here we see the segment elongated from fourteen divisions to 

 twenty divisions, i.e., it grew six divisions (= 6xl'82 = 10'92 /jC) 

 in the interval from 8.20 to 8.51 i.e., in thirty-one minutes giving 

 an average rate of growth of about 0'35 ft per minute, though 

 the rate of growth varies from time to time. 



Now the whole filament was 600 divisions long (= 1,092 /t), and 

 consisted of at least forty such segments,* and if each of them was 

 growing at anything like this rate, no wonder the filament pushed 

 this segment forward so quickly, for it would be elongating as a 

 whole at the rate of 14 fi per minute. 



To gain further information in this connection, I exchanged the 

 objective for the combination I usually employ for measuring, and 

 measured the growth ot about a third of the whole filament (including 

 the part here concerned) during the seven minutes from 9 to 9.7 P.M., 

 i.e., beginning 4^ minutes after the last measurement. 



At 9 P.M. the piece observed was 210 /t long, and at 9.7 P.M. it 

 had elongated to 250 /t, giving a growth of 40 n, which is at the 

 rate of 5'7 /t per minute. If this was going on through the rest 

 of the length, the filament as a whole would be growing at a rate 

 considerably in excess of my estimate. 



Now if we look at the distance through which the measured 

 segment was pushed during the thirty-one minutes' period given 

 above, we find it amounts to forty-five divisions (= 45 X 1'82 = 

 81'90 /t), so that even such numbers as I have proposed need not 

 seem extravagant, and indeed I have reason to know they are much 

 below the real ones in many cases. 



One of the most interesting cases of rapid growth I have seen is 

 the following. 



Spores sown in normal gelatine at 22 C. had germinated out to 

 filaments 80 100 /n long in o^ hours in the dark, and were then 

 put into the dark Sachs' boxf at 28 C. The temperature was then 

 slowly raised, so that in two hours it had risen to 34 C., half an 

 hour later to 38 C., and in the next quarter of an hour to 39 C. 

 By chance I happened now to catch a broken-off segment which 

 was growing at the maximum rate that precedes death at these 

 high temperatures. The measurements were as follows : 



* Almost certainly more than 40, but I could not determine accurately because 

 Uie last formed septa are not sufficiently distinct. 



f See p. 394 for description of this box and the method of using it. 



